Soluble oil



United States Patent SOLUBLE OIL James L. Jezl, Swarthmore, Pa.,.assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application November 13, 1952, Serial No. 320,354

8 Claims. (Cl. 252-33.3)

No Drawing.

This invention relates to soluble oil compositions comprising mineral oil, alkali metal soaps of carboxylic acids obtained by partial oxidation of mineral oil, and a particular class of added organic compounds.

It is known in the art to prepare soluble oil compositions emulsifiable in water to form oil-in-water emulsions by forming a mixture of mineral oil and alkali metal soap of carboxylic acids obtained by partial oxidation of mineral oil. Such compositions may be called for convenience synthetic soluble oils to distinguish them from soluble oil compositions which do not contain soaps of acidic products of oxidation of mineral oil. Major problems involved in the preparation of synthetic soluble oil compositions have been the obtaining of a stable, homo geneous mixture of oil and soap prior to emulsification, and the obtaining of a stable emulsion after einulsification. The present invention provides a highly stable, homogeneous mixture of oil and soap, and. a highly stable emulsion, these effects being obtained. by the incorporation in the soluble oil composition ofia particular class of organic compounds as .coupling agent or mutual solvent," i. e. solvent for both oil and water. The organic compound employed has a dual function since it both stabilizes the soluble oil prior to emulsification and stabilizes the emulsion after emulsification.

The organic compounds'employed in synthetic soluble oils according: to the invention are selected from the group consisting of dihydroxy alkanes having 8 to 10 carbon atoms inclusive and alkoxy diihydroxy alkanes having 9 to 11 carbon atoms inclusive. Straight or branched chain compounds and all the various position isomers can be employed. The organic compound is employed in minor proportion inthe-synthetic soluble oil according to the invention.

Alkanediols employed according to the invention should not have less than 8' carbon atoms; they should not, on the other hand, havemore than lOcarbon atoms. Similarly, alkoxy dihydroxy alkanes for use according to the invention should not have less than 9 carbon atoms nor more than 11 carbon atoms.

It is noted that 'a hidroxy alkane having 9 carbon atoms has 4.5 carbon atoms for each hydroxyl in the molecule, and that an alkoxy dihydroxy alkane having 10 carbon atoms hasla number of carbon atoms approximately equivalent to 4.5 carbon atoms for each hydroxyl and 1 carbon atoms for each ether linkage- It is believed that these relationships a re optimum for use of ithe type of compound employed according to the invention in a synthetic soluble oil composition. Slight variation from this optimum, as allowedby the ranges of carbon atoms specified previously is permissible, but satisfactory results are generally not obtained if the limits of permissible variation are exceeded.

The dihydroxy alkanes which can be used according to the invention include octanediols, nonanediols, and decanediols. Examples of suitable alkoxy dihydroxyalkanesfor use accordingto the invention are thefollowing: methoxv octanediols, methoxy nonanediols, methoxy decanediols, ethoxy heptanediols, propoxy heptanediols, butoxy heptanediols, pentoxy butanediols, hexyloxy propanediols, octyloxy propanediols, etc.

The soluble oil composition according to the present invention comprises mineral oil, alkali metal soap of carboxylic acids obtained by partial oxidation of mineral oil, and an organic compound as specified above. It is generally preferred that the composition should also contain other constituents such as petroleum sulfonates and small amounts of excess alkali metal hydroxide and water.

In some cases, it may be desirable to incorporate alkali metal soap of petroleum naphthenic acids in the soluble oil. Also, in some cases, it may be desirable to incorporate in the soluble oil the entire product of oxidation of mineral oil, rather than just a predominantly carboxylic acid portion thereof.

Preferably the sulfonate concentration of synthetic soluble oils according to the invention is sufiicient to provide a sulfonate saponification number equivalent of at least 3. Generally, the sulfonate saponification number equivalent is not greater than 10, more preferably not greater than 7. The sulfonate saponification number equivalent is determined by measurement, in mg. of KOH per gram, of the saponification number of the sulfonatecontaining material prior to mixing with other sfaponifiable components of the soluble oil, and multiplying the saponification number thus obtained by the weight fraction of the sulfonate-containing material in the compounded soluble oil.

Preferably, the concentration of carboXyl-containing materials in the soluble oils according to the invention is suflicient .to provide a carboxylate saponification number equivalent of at least 10, more preferably at least 14. Generally, the carboxylate saponification number equivalent is not greater than 20, more preferably not greater than 17. The carboxylate saponificaticn number equivalentmay be determined in a manner generally similar to that described for determination of sulfonate number equivalents.

The mineral lubricating oil employed in the soluble oil composition according to the invention preferably has S. U. viscosity at F. within the range from 40 to 120. The mineral oil which is used as oxidation charge, on the other hand, preferably has S. U. viscosity at 100 F. within the range from to 200. A preferred oxidation charge is petroleum foots oil, but mineral lubricating oils may also be used. Mineral oil, as the term is used in connection with the oxidation charge, is understood to include petroleum wax, preferably paraffin Wax havingmeltingipoint not greater than 100 F, as well as normally liquid oils.

Petroleum foots oil is the oily byproduct obtained in the deoiling of slack wax. When the deoiling is done by sweating, the foots oil is sometimes called sweat oil or sweater oil. When the deoiling is done by filtration of a solution of .the slack Wax in a solvent for oil, the filtrate obtained is a solution of foots oil in the solvent used, c. g. methyl ethyl ketone or mixtures thereof with toluene and/or benzene. Petroleum foots oil generally contains substantial amounts of low-melting wax in addition to lubricating oil, the amount of wax depending on the filtration temperature and other variables.

The oxidation charge should have suificiently low con- .tent of aromatic compounds so that there is no substantial gas, e. g. air, oxygen, ozonized air, etc. The oxidation is preferably conducted under atmospheric pressure or relatively low elevated pressure not exceeding, for example, 100 p. s. i. g. Such operation is advantageous in that the vent gases carry off some of the lower-boiling acidic products, which are undesirable in the soluble oil, and which in operation at higher pressures would remain in the liquid oxidation product. The oxidation is preferably conducted in the presence of an oxidation catalyst, such as manganese naphthenate, manganese soaps of fatty acids, manganese soaps of carboxylic acids obtained in previous oxidations of mineral oil, etc.

The oxidation preferably is continued at least until the saponification number of the liquid oxidation product is 60, and is terminated before the saponification number of the liquid oxidation product exceeds 120, preferably before the saponification number exceeds 100. Oxidation to too high a saponification number tends to result in for mation of oxidation products which have adverse effect in the soluble oil.

The synthetic soluble oils according to the invention are preferably alkaline, having for example free alkalinity within the range 0.01 to 0.12 percent as NaOH.

The organic compound employed according to the invention as a coupling agent or mutual solvent for synthetic soluble oils may be used if desired in conjunction with other known coupling agents or mutual solvents, e. g. monobutyl ether of ethylene glycol. Also, mixtures of two or more coupling agent according to the present invention may be employed.

A preferred range of coupling agent concentration in the soluble oil according to the invention is from 0.75 to 3.0 volume percent, more preferably from 1.25 to 2.5 volume percent. A preferred range of water concentration in the soluble oil is from 2.25 to 5.0 volume percent, more preferably from 2.5 to 3.25 volume percent. Generally, for a given soluble oil there should be at least a certain amount of coupling agent to obtain satisfactory results, but this amount varies for different properties and relative proportions of the other constituents of the soluble oil. Also, there should generally, for satisfactory results, be a water content within certain upper and lower limits, but these limits also vary for different properties and relative proportions of the other constituents of the soluble oil.

The following examples illustrate the invention:

Example I Synthetic soluble oils were prepared by mixing the following materials in the stated amounts:

Mineral lubricating oil grams 490 Partially oxidized foots oil -do 108 Petroleum naphthenic acids do 140 Petroleum mahogany sulfonates (10.9% solution in mineral oil) "grams" 250 Caustic soda, 50 B milliliters 17 adjusting the water content of the soluble oil at various levels, and adding an octanediol (2-ethyl-1,3-hexanediol) in various amounts.

The lubricating oil used had S. U. viscosity at 100 F. of about 100. The naphthenic acids had saponification number of 61. The petroleum sulfonates were sodium soaps of sulfonic acids having saponification number of 13.2, and contained 1.80 weight percent organic $03.

The oxidized foots oil was prepared by partially oxidizing a foots oil obtained in the solvent deoiling of slack wax, the oxidation being performed at 260320 F. and atmospheric pressure by blowing air through the foots oil in the presence of a manganese-naphthenate containing catalyst. The oxidation was continued until the saponification number of the liquid oxidation product was 78.0 and 108 grams of that product was incorporated in the soluble oil.

The naphthenic acids and oxidized foots oil each contributed 8.5 saponification number equivalent to the soluble oils, and the sulfonates contributed 3.3 saponification number equivalent. The compounded soluble oil had free alkalinity of about 0.09-0.10 percent as NaOH.

Each soluble oil composition was tested for stability by allowing it to stand at 10 F. for 48-72 hours and then observing the oil at room temperature to determine whether any oil had separated from the soluble oil to form an upper oil layer, and whether there were any signs of haziness or gelation in the soluble oil. Each soluble oil was rated as stable if there were no discernible oil separation, haziness, or gelation; otherwise, unstable.

Each soluble oil was also tested for emulsion stability by emulsifying 10 ml. of the soluble oil in ml. of added 45 F. tap water having calcium hardness of less than p. p. m. as CaCOs, and allowing the emulsion to come to room temperature while standing for 24 hours, at the end of which time the appearance of the emulsion was observed to determine whether or not it was stable. If the emulsion surface was bright, or if it was only slightly dull, with very little or no cream on the surface, the emulsion was rated stable. If there was a substantial amount of cream or scum or free oil on the emulsion surface, the emulsion was rated unstable.

The following table shows the results obtained with various combinations of water content and octanediol content:

Vol. Vol. Percent Percent Oil Emulsion Water Octane- Stability Stability diol In the absence of the octanediol, the oil and the emulsion are both unstable.

The above table shows that satisfactory results are obtained with water contents from 3.0 to 4.0 volume percent and octanediol contents from 1.0 to 2.0 volume percent.

Example 11 V01. V01. Percent Oil Emulsion Percent Methoxy- Stability Stability Water Octanediol 2. 5 2. 0 Stable Stable. 3.0 1.0 .do D0. 3.0 1.5 .do Do. 3. 0 2. 0 do Do.

This table shows that satisfactory results are obtained with water contents from 2.5 to -3.0 volume percent and methoxy octanediol contents from 1.0 to 2.0 percent.

Example 111 Synthetic soluble oils were prepared according to the same procedure described in Example I except that an ethoxyoctanediol (2 ethoxyrnethyl-ZA-dimethyl-1,S-penitanediol) was employed in place of the octanediol of Example I. The following table shows the results obtained with various combinations of water content and lethoxyoctanediol content:

V01. Percent Oil Emulsion Percent Ethoxy- Stability Stability Water Octane- 3.0 1.5 Stable Stable.

3.0 2.0 do Do.

3.5 1.5 do D0.

Flhis table shows that satisfactory results are obtained with water contents from 3.0 to 4.0 percent and ethoxyoctanediol contents from 1.5 to 2.0 percent.

Example IV I Synthetic soluble oils were prepared by the same method disclosed in Example I, employing various percentages of water and an octanediol (2-ethyl-1,3-hexanediol). The soluble oils were tested for emulsion stability in hard water emulsions. The water used had hardness equivalent to 300 p. p. m. OaCOs and 100 p. p. m. NaCl. ml. of each soluble oil were emulsified in 90 ml. of 45 F. hard water andallowed to come to room temperature while standing for 24 hours, at the end of which time each emulsion was rated for stability. If the emulsion surface was bright, or if there was only slight cream or scum on the surface the emulsion was rated stable. If there was heavy cream or scum, or free oil on the emulsion surface, the emulsion was rated unstable. The tap water emulsions as prepared in the preceding examples are rated somewhat more rigorously than the hard water emulsions of the present example, since hard water emulsions generally tend to be less stable than tap water emulsions, and a higher standard must therefore be used for tap water emulsions, in order to provide that in the majority of instances a given soluble oil which gives satisfactory tap water emulsions will also give satisfiactory hard water emulsions.

The following results were obtained, the oil stabilities being determined after allowing the soluble oil to stand for one month at 70 F.

This table shows that satisfactory results are obtained in hard water emulsions, with water contents from 2.8 to 3.8 and octanediol contents from 1.25 to 1.75.

Example V Synthetic soluble oils were prepared by the same method disclosed in Example 11, employing various amounts of Water and of a methoxyoctanediol (Z-methoxymethyl- 2,4-dimethyl-1,5-pentanediol). The soluble oils were tested for emulsion stability in hard water emulsions as described in Example IV. The following results were obtained:

V01. V01. Percent 011 Emulsion Percent Methoxy- Stability Stability Water Octanedial 2. 6 1. 25 Stablei-- Stable 2. 6 1. 5 d0 D0. 2. 6 1. 75 Do. 2. 8 l. 25 Do. 2. 8 1. 5 Do. 2. 8 1. 75 Do.

This table shows that satisfactory results are obtained in hard water emulsions with water contents from 2.6 to 2.8 and methoxyoctanediol contents from 1.25 to 1.75.

Example VI Synthetic soluble oils were prepared by the same method disclosed in Example Ill, employing various amounts of water and of an ethoxy octanediol (Z-ethoxymethyl-2,4-dimethyl-l,S-pentanediol). The soluble oils were tested in hard water emulsions as described in Example IV. The following resultswere obtained:

Vol. Ier- Vol.Percent Oil Sta- Emulsion cent Ethoxybility Stability Water octanediol Preferred Preferred Coupling Agent Coupling Water 0011- Agent Concentration centration 2-ethyl-1,3-hexanediol 0. 75 t0 3. 0 2. 75 to 5.0 2 methoxymethyl 2,4. dimethyl 1,5-

pentanediol 0.75 to 3.0 2. 25 to 3. 25 2 ethoxymethyl 2,4 dimethyl 1,5-

pentanediol 1.25 to 3.0 2. 25 to 4. 25

The properties of the oxidation product which is employed in synthetic soluble oils afiects substantially the ease with which oil stability and emulsion stability can be imparted to the soluble oil by use of a coupling agent. The coupling agents according to the invention are particularly advantageous in that they are capable of imparting oil stability and emulsion stability to synthetic soluble oils which contain an oxidation product which makes the soluble oil relatively quite ditficult to stabilize.

The invention claimed is:

l. A soluble oil composition comprising: mineral lubrieating oil; alkali metal soap of petroleum. mahogany sulfonic acids; alkali metal soap of petroleum naphthenic acids; a saponified oxidation product mixture obtained by partially oxidizing petroleum foots oil in liquid phase at a temperature in the range from 260 F. to 320 F. and a pressure from atmospheric to p. s. i. g. in the presence of a metallic oxidation catalyst until the saponification number of the oxidation product mixture is within the range from 60 to 120 mg. of KOH per gram, and saponifying said oxidation product mixture with an alkali metal basic compound; 2.25 to 5.0 volume percent of water; and 0.75 to 3.0 volume percent of an organic compound selected from the group consisting of a dihydroxy alkane having 8 to 10 carbon atoms inclusive and an alkoxy dihydroxy alkane having 9 to 11 carbon atoms inclusive; said soluble oil having sulfonate saponification number equivalent within the approximate range from 3 to 10 mg. of KOH per gram and carboxylate saponification number equivalent within the approximate range from 10 to 20 mg. of KOH per gram, said saponified oxidation product mixture providing carboxylate saponification number equivalent within the approximate range from to mg. of KOH per gram and said alkali metal soap of petroleum naphthenic acids providing carboxylate saponification number equivalent within the approximate range from 5 to 10 mg. of KOH per gram.

2. A soluble oil composition comprising: mineral lubricating oil having S. U. viscosity at 100 F. within the range from 40 to 120 seconds; alkali metal soap of petroleum mahogany sulfonic acids; alkali metal soap of petroleum naphthenic acids; a saponified oxidation product mixture obtained by partially oxidizing petroleum foots oil in liquid phase at a temperature in the range from 260 F. to 320 F. and a pressure from atmospheric to 100 p. s. i. g. in the presence of a metallic oxidation catalyst until the saponification number of the oxidation product mixture is Within the range from 60 to 120 mg. of KOH per gram, and saponifying said oxidation product mixture with an alkali metal basic compound; 2.25 to 5.0 volume percent of water; and 0.75 to 3.0 volume percent of an organic compound selected from the group consisting of a dihydroxy alkane having 8 to 10 carbon atoms inclusive and an alkoxy dihydroxy alkane having 9 to 11 carbon atoms inclusive; said soluble oil having sulfonate saponification number equivalent within the approximate range from 3 to 10 mg. of KOH per gram and carboxylate saponification number equivalent within the approximate range from 10 to 20 mg. of KOH per gram, approximately half of said carboxylate saponification number equivalent being supplied by said oxidation product mixture.

3. Composition according to claim 1 wherein said organic compound is an octanediol.

4. Composition according to claim 1 wherein organic compound is 2-ethyl-1,3-hexanediol.

5. Composition according to claim 1 wherein said organic compound is a methoxyoctanediol.

6. Composition according to claim 1 wherein said organic compound is 2methoxymethyl-2,4dimethyl-1,5- pentanediol.

7. Composition according to claim 1 wherein said organic compound is an ethoxyoctanediol.

8. Composition according to claim 1 wherein said organic compound is 2-ethoxymethyl-2,4-dimethyl-1,5- pentanediol.

said

References Cited in the file of this patent UNITED STATES PATENTS 2,043,922 Burwell June 9, 1936 2,470,913 Bjorksten May 24, 1949 2,606,874 Garner et a1 Aug. 12, 1952 2,617,769 Nichols Nov. 11, 1952 OTHER REFERENCES Metal Working Lubricants, by Bastian, McGraw-Hil] Pub. Co., 1951, page 6.

Higher Diols, pamphlet by Carbide and Carbon Chem. Corp. Patent Oflice date Mar. 27, 1950. 8 pp. 

1. A SOLUBLE OIL COMPOSITION COMPRISING: MINERAL LUBRICATING OIL; ALKALI METAL SOAP OF PETROLEUM MAHOGANY SULFONIC ACIDS; ALKALI METAL SOAP OF PETROLEUM NAPHTHENIC ACIDS; A SAPONIFIED OXIDATION PRODUCT MIXTURE OBTAINED BY PARTIALLY OXIDIZING PETROLEUM FOOTS OIL IN LIQUID PHASE AT A TEMPERATURE IN THE RANGE FROM 260* F. TO 320* F. AND A PRESSURE FROM ATMOSPHERIC TO 100 P. S. I. G. IN THE PRESENCE OF A METALLIC OXIDATION CATALYST UNTIL THE SAPONIFICATION NUMBER OF THE OXIDATION PRODUCT MIXTURE IS WITHIN THE RANGE FROM 60 TO 120 MG. OF KOH PER GRAM, AND SAPONIFYING SAID OXIDATION PRODUCT MIXTURE WITH AN ALKALI METAL BASIC COMPOUND; 2.25 TO 5.0 VOLUME PERCENT OF WATER; AND 0.75 TO 3.0 VOLUME PERCENT OF AN ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF A DIHYDROXY ALKANE HAVING 8 TO 10 CARBON ATOMS INCLUSIVE AND AN ALKOXY DIHYDROXY ALKANE HAVING 9 TO 11 CARBON ATOMS INCLUSIVE; SAID SOLUBLE OIL HAVING SULFONATE SAPONIFICATION NUMBER EQUIVALENT WITHIN THE APPROXIMATE RANGE FROM 3 TO 10 MG. OF KOH PER GRAM AMD CARBOXYLATE SAPONIFICATION NUMBER OF EQUIVALENT WITHIN THE APPROXIMATE RANGE FROM 10 TO 20 MG. OF KOH PER GRAM, SAID SAPONIFICATION NUMBER EQUIVALENT WITHIN THE APPROXIMATE RANGE CATION NUMBER EQUIVALENT WITHIN THE APPROXIMATE RANGE FROM 5 TO 10 MG. OF KOH PER GRAM AND SAID ALKALI METAL SOAP OF PETROLEUM NAPHTHENIC ACIDS PROVIDING CARBOXYLATE SAPONIFICATION NUMBER EQUIVALENT WITHIN THE APPROXIMATE RANGE FROM 5 TO 10 MG. KOH PER GRAM. 